#include <iostream>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <cmath>
typedef std::pair<int, int> PII;
std::vector<PII> v;
bool cmp(PII a, PII b)
{
    return (a.second*1.0)/(a.first*1.0) > (b.second*1.0)/(b.first*1.0);
}
int main()
{
    int N, T;
    scanf("%d%d", &N, &T);
    for (int i = 0; i < N; i++)
    {
        int a, b;
        scanf("%d%d", &a, &b);
        v.push_back(std::make_pair(a, b));
    }

    sort(v.begin(), v.end(), cmp);

    double res = 0;
    double t = T*1.0;
    for (int i=0; i < N; i++)
    {
        if (t >= v[i].first)
        {
            res += v[i].second;
            t -= v[i].first;
        }
        else
        {
            res += (t/v[i].first)*v[i].second;
            break;
        }
    }

    printf("%.2f\n", res);
    return 0;
}